METHOD AND APPARATUS FOR GENERATING AND PROCESSING MAC-ehs PROTOCOL DATA UNITS

ABSTRACT

A network device and wireless transmit/receive unit (WTRU) using an enhanced high speed medium access control (MAC-ehs) are disclosed. A network device may provide a MAC-ehs reordering protocol data unit (PDU) with a segment of a service data unit (SDU). A MAC-ehs PDU is generated including the MAC-ehs reordering PDU. The MAC-ehs PDU is sent via a high speed downlink shared channel (HS-DSCH). The WTRU disassembles MAC-ehs PDUs to provide reordering PDUs that each may include a segment of a MAC-ehs SDU. The WTRU may reassemble a MAC-ehs SDU with the segment of the MAC-ehs SDU from at least one of the reordering PDUs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 12/044,285 filed Mar. 7, 2008, which claims the benefit of U.S. provisional application No. 60/893,577 filed Mar. 7, 2007, the contents of which are hereby incorporated by reference herein.

FIELD OF INVENTION

The present invention is related to wireless communications.

BACKGROUND

High speed packet access (HSPA) evolution refers to the third generation partnership project (3GPP) radio access technology evolution of high speed downlink packet access (HSDPA) and high speed uplink packet access (HSUPA). Some of the major goals of HSPA evolution include higher data rates, higher system capacity and coverage, enhanced support for packet services, reduced latency, reduced operator costs and backward compatibility.

It has been agreed that an enhanced high speed medium access control (MAC-ehs) entity is extended to include a function for segmentation and multiplexing from different priority queues in addition to being able to receive radio link control (RLC) protocol data units (PDUs) of flexible size. The addition of new MAC-hs functionalities requires modification to the conventional MAC-hs architecture.

FIG. 1 shows a universal terrestrial radio access network (UTRAN) side MAC-ehs entity 100 proposed for HSPA evolution. In the proposed MAC-ehs architecture, segmentation is performed per logical channel by segmentation entities 112. The segmented MAC-ehs service data units (SDUs) are then multiplexed by the logical channel identity (LCH-ID) multiplexing entities 114 based on the logical channel identity, and buffered in the configured priority queue 116. A MAC-ehs protocol data unit (PDU) is then generated from the MAC-ehs SDUs stored in the priority queue 116 and transmitted via a hybrid automatic repeat request (HARQ) entity 120.

FIG. 2 shows a user equipment (UE) side MAC-ehs entity 200 proposed for HSPA evolution. The received MAC-ehs PDU via an HARQ entity 202 is disassembled into reordering PDUs by the disassembly entity 204. The reordering PDUs are distributed to a reordering queue 208 by the reordering queue distribution entity 206 based on the received logical channel identifier. The reordering PDUs are reorganized according to the transmission sequence number (TSN). Reordering PDUs with consecutive TSNs are delivered to a higher layer upon reception. A timer mechanism determines delivery of non-consecutive data blocks to higher layers. There is one reordering entity 208 for each priority class. An LCH-ID demultiplexing entity 210 routes the reordered reordering PDUs to a reassembly entity 212 based on the logical channel identifier. The reassembly entity 212 reassembles segmented MAC-ehs SDUs to original MAC-ehs SDUs and forwards the MAC-ehs SDUs to upper layers.

The proposed MAC-ehs entity 100 for the UTRAN-side performs segmentation on a per logical channel basis. However, the segmentation of the MAC-d PDUs should not be performed at that level, since the packet will not be transmitted immediately. The multiplexed reordering PDUs are buffered in the priority queue 116 and sent at a later time. Segmentation of the MAC-ehs SDUs prior to knowing the exact channel conditions is inefficient. The segmentation should not be performed prior to the time interval in which the packets will be transmitted. It would be desirable that the segmentation be performed at the time when the MAC-ehs PDU is created and the size of the transport block (TB) for that transmission time interval (TTI) is known. In addition, if the UTRAN is updated to segment the MAC-ehs SDUs right before the MAC-ehs SDUs are sent, the WTRU must also be updated accordingly.

In the proposed MAC-ehs entity 200 in FIG. 2, the LCH-ID de-multiplexing entity 210 routes the MAC-ehs segments to the reassembly entity 212 based on the logical channel identity. This requires reassembly entities for different logical channels within the same queue. In addition, if MAC-ehs headers are optimized, the system information (SI) field will not be present for every logical channel, but it will be present only for the priority queue.

SUMMARY

A method and apparatus for generating and processing a MAC-ehs PDU are disclosed. In a Node-B, MAC-ehs SDUs received from an upper layer are multiplexed based on a logical channel identity. Reordering PDUs are generated from the multiplexed MAC-ehs SDUs from different logical channels mapped to a priority queue. A reordering PDU includes at least one MAC-ehs SDU and/or at least one MAC-ehs SDU segment. A MAC-ehs SDU is segmented on a priority class basis if a MAC-ehs SDU does not fit into a reordering PDU. A MAC-ehs PDU is generated including at least one reordering PDU. The multiplexed MAC-ehs SDUs may be stored in a corresponding priority queue before generating the reordering PDUs. Alternatively, the reordering PDUs may be generated from the multiplexed MAC-ehs SDUs and the reordering PDUs may be stored in a corresponding priority queue. Alternatively, the received MAC-ehs SDUs may be buffered in a corresponding buffer for each logical channel before multiplexed based on a logical channel identity, or reordering PDUs are generated.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description, given by way of example and to be understood in conjunction with the accompanying drawings wherein:

FIG. 1 shows a UTRAN-side MAC-ehs entity proposed for HSPA evolution;

FIG. 2 shows a UE-side MAC-ehs entity proposed for HSPA evolution;

FIGS. 3-4 show a UTRAN-side MAC-ehs entity in accordance with one embodiment;

FIG. 5 shows a UTRAN-side MAC-ehs entity in accordance with another embodiment;

FIGS. 6-8 show a UTRAN-side MAC-ehs entity in accordance with another embodiment;

FIG. 9 shows a UTRAN-side MAC-ehs entity in accordance with another embodiment; and

FIG. 10 shows a WTRU-side MAC-ehs entity in accordance with one embodiment.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a UE, a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “Node-B” includes but is not limited to a base station, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.

The terminology “MAC-ehs payload unit” or “payload unit” will refer to a MAC-ehs SDU or a MAC-ehs SDU segment that is inserted as a payload of a MAC-ehs PDU. The terminology “MAC-d flow” and “logical channel” are used interchangeably, and use of one term does not exclude the other. The terminology “reordering PDU” refers to one unit of a MAC-ehs PDU. The MAC-ehs PDU may include one or more reordering PDUs. The reordering PDU may include one or more payload units. The MAC-ehs SDU may be a MAC-d PDU, MAC-c/sh/m PDU, or the like.

FIG. 3 shows a UTRAN-side MAC-ehs entity 300 in accordance with one embodiment. The MAC-ehs entity 300 includes a scheduling and priority handling entity 310, an HARQ entity 320, and a transport format and resource combination (TFRC) selection entity 330. The scheduling and priority handling entity 310 includes LCH-ID multiplexing entities 312, priority queues 314, segmentation entities 316, and a priority queue multiplexing entity 318. The scheduling and priority handling entity 310 manages HS-DSCH resources for data flows according to their priority class. The HARQ entity 320 handles HARQ functionality for supporting multiple instances (HARQ process) of stop and wait HARQ protocols. The TFRC selection entity 330 selects a TFRC.

The MAC-ehs entity 300 receives MAC-ehs SDUs from an upper layer, (e.g., MAC-d or MAC-c entity (not shown)). The LCH-ID multiplexing entity 312 may multiplex the MAC-ehs SDUs from multiple logical channels based on the scheduling decision and the TFRC selected by the TFRC selection entity 330 The TFRC selection entity 330 indicates to the scheduling and priority handling entity 310 the size of the MAC-ehs PDU and thus the size of data to be transmitted from each queue into a reordering PDU to be transmitted on a TTI basis. The multiplexed MAC-ehs SDUs are stored in a priority queue 314.

The segmentation entity 316 may segment the MAC-ehs SDUs per priority queue. The segmentation entity 316 segments a MAC-ehs SDU if the MAC-ehs SDU does not fit into a reordering PDU. For example, if the MAC-ehs SDU to be included in the reordering PDU is greater than the size of the reordering PDU or it causes the sum of payload units to exceed the size of the selected reordering PDU, the segmentation entity 316 segments the MAC-ehs SDU. In this case, the reordering PDU includes only one segment of the MAC-ehs SDU. The remaining segment of the MAC-ehs SDU after segmentation is stored in the segmentation entity and may be transmitted as the first payload unit in the next reordering PDU for the priority queue if the remaining segment fits into the next reordering PDU. The remaining segment of the MAC-ehs SDU is segmented again if the remaining segment still does not fit into the next reordering PDU. This may be repeated until all the parts of the MAC-ehs SDU have been transmitted. The reordering PDU will contain at most two segments, one at the beginning and one at the end, and may include zero, one, or more than one complete MAC-ehs SDUs.

The segmentation entity 316 may base its segmentation decision on the current channel condition, the given transport format and resource combination (TFRC) selection, the reordering PDU size, and the like. The segmentation is performed on a priority queue basis instead of on a per logical channel basis.

The priority queue multiplexing entity 318 may perform multiplexing of reordering PDUs in one MAC-ehs PDU. The priority queue multiplexing entity 318 selects one or more reordering PDUs from one or more priority queues 316 in order to create the MAC-ehs PDU based on the TFRC selection.

The priority queue multiplexing entity 318 may be incorporated into the HARQ entity 320. The TFRC selection entity 330 may be attached to the scheduling and priority handling entity 310, as shown in FIG. 4.

FIG. 5 shows a UTRAN-side MAC-ehs entity 500 in accordance with another embodiment. In this embodiment, the segmentation is performed on a priority queue basis after logical channel multiplexing. The MAC-ehs entity 500 includes a scheduling and priority handling entity 510, an HARQ entity 520, and a TFRC selection entity 530. The scheduling and priority handling entity 510 includes LCH-ID multiplexing entities 512, segmentation entities 514, priority queues 516, and a priority queue multiplexing entity 518. The scheduling and priority handling entity 510 manages HS-DSCH resources for data flows according to their priority class. The HARQ entity 520 handles HARQ functionality for supporting multiple instances (HARQ process) of stop and wait HARQ protocols. The TFRC selection entity 530 selects a TFRC.

The MAC-ehs entity 500 receives MAC-ehs SDUs from an upper layer. The LCH-ID multiplexing entity 512 may multiplex MAC-ehs SDUs from multiple logical channels based on the scheduling decision and optionally based on the TFRC selected by the TFRC selection entity 530. The TFRC selection entity 530 indicates to the scheduling and priority handling entity 510 the size of the MAC-ehs PDU to be transmitted on a TTI basis.

The MAC-ehs SDUs, after the logical channel multiplexing, may be segmented by the segmentation entity 514. The segmentation entity 514 segments a MAC-ehs SDU if the MAC-ehs SDU does not fit into a reordering PDU based on the TRFC selection. The reordering PDU contains at most two segments, one at the beginning and one at the end, and may include zero, one, or more than one MAC-ehs SDUs.

Reordering PDUs are stored in a priority queue 516. The priority queue multiplexing entity 518 may perform multiplexing of reordering PDUs in one MAC-ehs PDU. The priority queue multiplexing entity 518 selects one or more reordering PDUs from the priority queues 516 in order to create the MAC-ehs PDU.

The priority queue multiplexing entity 518 may be incorporated into the HARQ entity 520. The TFRC selection entity 530 may be attached to the scheduling and priority handling entity 510.

FIG. 6 shows a UTRAN-side MAC-ehs entity 600 in accordance with another embodiment. In this embodiment, the MAC-ehs SDUs are buffered per logical channel and segmentation is performed on a priority queue basis after logical channel multiplexing. The MAC-ehs entity 600 includes a scheduling and priority handling entity 610, an HARQ entity 620, and a TFRC selection entity 630. The scheduling and priority handling entity 610 includes queues 612, LCH-ID multiplexing entities 614, segmentation entities 616, priority handling entities 618, and a priority queue multiplexing entity 619. The scheduling and priority handling entity 610 manages HS-DSCH resources for data flows according to their priority class. The HARQ entity 620 handles HARQ functionality for supporting multiple instances (HARQ process) of stop and wait HARQ protocols. The TFRC selection entity 630 selects a TFRC.

The MAC-ehs entity 600 receives MAC-ehs SDUs from upper layers. MAC-ehs SDUs are stored in queues 612 on a logical channel basis. Alternatively, the queues 612 may not be present and data from different logical channels may flow directly from upper layers to the corresponding LCH-ID multiplexing entities 614. The LCH-ID multiplexing entities 614 multiplexes MAC-ehs SDUs stored in the queues 612 or received from the corresponding logical channels based on scheduling decision, scheduling priority and the TFRC selected by the TFRC selection entity 630. Based on the TFRC selection and the selected reordering PDU size, the MAC-ehs SDUs may be segmented by the segmentation entity 616. The segmentation entity 616 segments a MAC-ehs SDU if the MAC-ehs SDU does not fit into a reordering PDU. For example, if the MAC-ehs SDU to be included in the reordering PDU is greater than the size of the reordering PDU or it causes the sum of payload units to exceed the size of the reordering PDU, the segmentation entity 316 segments the MAC-ehs SDU. In this case, the reordering PDU includes only one segment of the MAC-ehs SDU. The remaining segment of the MAC-ehs SDU after segmentation is stored in the segmentation entity 616 and may be transmitted as the first payload unit in the next reordering PDU for the priority queue if the remaining segment fits into the next reordering PDU. The remaining segment of the MAC-ehs SDU is segmented again if the remaining segment still does not fit into the next reordering PDU. This may be repeated until all the parts of the MAC-ehs SDU have been transmitted. The reordering PDU contains at most two segments, one at the beginning and one at the end, and may include zero, one, or more than one MAC-ehs SDUs.

The priority handling entity 618 defines relative priorities between sets of logical channels (and/or MAC-d flows), and optionally assigns TSNs. The priority queue multiplexing entity 619 performs multiplexing of reordering PDUs in one MAC-ehs PDU.

The priority handling entity 618 and its functionalities may be incorporated in the priority queue multiplexing entity 619, as shown in FIG. 7, (i.e., priority queue multiplexing and TSN setting entity 702). The segmentation entity 616 or the LCH-ID multiplexing entity 614 may be extended to buffer segments of the MAC-ehs SDUs. The TFRC selection entity 630 may be attached to the scheduling and priority handling entity 610, as shown FIG. 8.

FIG. 9 shows a UTRAN-side MAC-ehs entity 900 in accordance with another embodiment. In this embodiment, the MAC-ehs SDUs are buffered per logical channel. Alternatively, the queues 912 may not be present and data from different logical channels may flow directly from upper layers to the corresponding segmentation entities 914. Segmentation is performed per logical channel on a TTI basis after the buffering. The MAC-ehs SDUs are buffered per logical channel rather than per priority queue. The MAC-ehs entity 900 includes a scheduling and priority handling entity 910, an HARQ entity 920, and a TFRC selection entity 930. The scheduling and priority handling entity 910 includes queues 912, segmentation entities 914, LCH-ID multiplexing entities 916, priority handling entities 918, and a priority queue multiplexing entity 919. The scheduling and priority handling entity 910 manages HS-DSCH resources for data flows according to their priority class. The HARQ entity 920 handles HARQ functionality for supporting multiple instances (HARQ process) of stop and wait HARQ protocols. The TFRC selection entity 930 selects a TFRC.

The MAC-ehs entity 900 receives MAC-ehs SDUs from upper layers. MAC-ehs SDUs from logical channels, (or MAC-d flows), are stored in queues 912 for each logical channel or alternatively are directly delivered from upper layers without any buffering. The MAC-ehs SDUs may then be segmented by the segmentation entity 914. The segmentation entity 914 segments a MAC-ehs SDU if the MAC-ehs SDU does not fit into a reordering PDU as selected by the TFRC selection. The reordering PDU contains at most two segments, one at the beginning and one at the end, and may include zero, one, or more than one MAC-ehs SDUs. The LCH-ID multiplexing entity 916 then multiplexes reordering PDUs from multiple logical channels, (i.e., multiple MAC-d flows), based on the scheduling decision and the TFRC selected by the TFRC selection entity 930.

The priority handling entity 918 defines relative priorities between sets of logical channels (and/or MAC-d flows), and optionally assigns TSNs. Alternatively, the TSNs setting may be performed per logical channel instead of per priority queue. The priority queue multiplexing entity 919 performs multiplexing of reordering PDUs in one MAC-ehs PDU. The priority handling entity and its functionality 918 may be incorporated in the priority queue multiplexing entity 919. Alternatively, the LCH-ID MUX and priority queue multiplexing may be combined in one entity and multiplexing may be performed only on one level, on a logical channel basis.

The segmentation entity 914 or the LCH-ID multiplexing entity 916 may be extended to buffer outstanding segments of the MAC-ehs SDUs. The TFRC selection entity 930 may be attached to the scheduling and priority handling entity 910.

FIG. 10 shows a WTRU-side MAC-ehs entity 1000 in accordance with one embodiment. Since in the UTRAN may perform segmentation after multiplexing logical channels in the mapped priority queue, the conventional WTRU-side MAC-ehs entity is modified to reflect these changes and to perform the reassembly and de-multiplexing in the same order. If segmentation is performed on a per priority queue basis, reassembly should be based on the reordering queue segmentation information.

The MAC-ehs entity 1000 includes an HARQ entity 1002, a disassembly entity 1004, a reordering queue distribution entity 1006, reordering queues 1008, SDU disassembly entities 1010, reassembly entities 1012, and LCH-ID demultiplexing entities 1014. The transmitted MAC-ehs PDUs are received via the HARQ entity 1002. The disassembly entity 1004 disassembles the MAC-ehs PDU to reordering PDUs. The reordering queue distribution entity 1006 distributes the reordering PDUs to an appropriate reordering queue 1008 based on the logical channel identity. The reordering PDUs are reordered at the reordering queue 1008 based on the TSN. The SDU disassembly entity 1010 disassembles MAC-ehs SDUs and segmented MAC-ehs SDUs from the reordered reordering PDUs, and delivers them to the reassembly entity 1012. The reassembly entity 1012 reassembles segmented MAC-ehs SDUs to original MAC-ehs SDUs for every reordering PDU and forwards the completed and reassembled MAC-ehs SDUs to the LCH-ID demultiplexing entity 1014. The LCH-ID demultiplexing entity 1014 routes the complete MAC-ehs SDUs to the correct logical channel, or MAC-d flow. Optionally, the SDU disassembly entity 1010 and the reassembly entity 1012 may be combined to one entity.

Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).

Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine.

A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) module. 

What is claimed is:
 1. A network device comprising: circuitry configured to receive a service data unit (SDU) from at least one logical channel; a priority queue configured to have the SDU, wherein the priority queue comprises SDUs from other logical channels; a segmentation function associated with the priority queue and configured to provide an enhanced high speed medium access control (MAC-ehs) reordering protocol data unit (PDU), the MAC-ehs reordering PDU including a segment of the SDU in the priority queue; circuitry configured to generate a MAC-ehs PDU including the MAC-ehs reordering PDU; and circuitry configured to send the MAC-ehs PDU via a high speed downlink shared channel (HS-DSCH).
 2. The network device of claim 1 wherein the received SDU is a MAC-ehs SDU.
 3. The network device of claim 1 further comprising: the circuitry further configured to receive a plurality of SDUs via a plurality of logical channels.
 4. The network device of claim 1 wherein the segmentation function is configured to segment the SDU into a plurality of segments, wherein the plurality of segments includes the segment from the SDU.
 5. The network device of claim 1 wherein the segmentation function is configured to segment based on any one of a current channel condition, a selected transport format and resource combination (TFRC), or a size of the MAC-ehs reordering PDU.
 6. The network device of claim 1 wherein the segmentation function is configured to generate a first reordering PDU and a second reordering PDU, and the network device comprises circuitry configured to include the first reordering PDU and the second reordering PDU in the MAC-ehs PDU.
 7. A method performed by a network device, the method comprising: receiving, by the network device, a service data unit (SDU) from at least one logical channel; providing, by the network device, the SDU to a priority queue, wherein the priority queue comprises SDUs from other logical channels; generating an enhanced high speed medium access control (MAC-ehs) reordering protocol data unit (PDU), the MAC-ehs reordering PDU including a segment of the SDU in the priority queue, wherein the SDU is segmented by a segmentation function associated with the priority queue; generating, by the network device, a MAC-ehs PDU including the MAC-ehs reordering PDU; and sending, by the network device, the MAC-ehs PDU via a high speed downlink shared channel (HS-DSCH).
 8. The method of claim 7 wherein the received SDU is a MAC-ehs SDU.
 9. The method of claim 7 further comprising: receiving, by the network device, a plurality of SDUs via a plurality of logical channels.
 10. The method of claim 7 wherein the segmentation function segments the SDU into a plurality of segments, wherein the plurality of segments includes the segment from the SDU.
 11. The method of claim 7 wherein the segmentation function segments based on any one of a current channel condition, a selected transport format and resource combination (TFRC), or a size of the MAC-ehs reordering PDU.
 12. The method of claim 7 wherein the segmentation function is configured to generate a first reordering PDU and a second reordering PDU, and the network device provides the first reordering PDU and the second reordering PDU in the MAC-ehs PDU.
 13. A wireless transmit/receive unit (WTRU) comprising: circuitry configured to receive, at an enhanced high speed medium access control (MAC-ehs), MAC-ehs protocol data units (PDUs); circuitry configured to disassemble the MAC-ehs PDUs to provide reordering PDUs, wherein each reordering PDU includes a complete MAC-ehs service data unit (SDU) and a segment of another MAC-ehs SDU; circuitry configured to reassemble a MAC-ehs SDU with the segment of the another MAC-ehs SDU from at least one of the reordering PDUs; and wherein the reassembled MAC-ehs SDU is provided to a logical channel of a plurality of logical channels based on a logical channel identifier.
 14. The WTRU of claim 13 wherein the reception of the MAC-ehs PDUs is performed by a hybrid automatic repeat request (HARQ) function.
 15. The WTRU of claim 13 further comprising: the WTRU is configured to reassemble segmented MAC-ehs SDUs to a MAC-ehs SDU for every reordering PDU.
 16. A method performed by a wireless transmit/receive unit (WTRU), the method comprising: receiving, by the WTRU, at an enhanced high speed medium access control (MAC-ehs), MAC-ehs protocol data units (PDUs); disassembling, by the WTRU, the MAC-ehs PDUs to provide reordering PDUs, wherein each reordering PDU includes a complete MAC-ehs service data unit (SDU) and a segment of another MAC-ehs SDU; reassembling, by the WTRU, a MAC-ehs SDU with the segment of the another MAC-ehs SDU from at least one of the reordering PDUs; and wherein the reassembled MAC-ehs SDU is provided to a logical channel of a plurality of logical channels based on a logical channel identifier.
 17. The method of claim 16 wherein the reception of the MAC-ehs PDUs is performed by a hybrid automatic repeat request (HARQ) function.
 18. The method of claim 16 further comprising: reassembling, by the WTRU, segmented MAC-ehs SDUs to a MAC-ehs SDU for every reordering PDU. 